砂黄土高边坡稳定性的数值模拟研究
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摘要
基于野外调查和室内试验分析,阐述了黄土高原北部砂黄土边坡破坏的主要形式及其影响因素。结合陕北高等级公路建设,采用弹塑性有限元法模拟了不同工程开挖条件下坡形、降雨和地震作用等因素对砂黄土高边坡稳定性的影响。结果表明,随着坡角或坡高的增大,边坡稳定性不断变差,阶状坡形比一坡到顶的坡形更利于边坡稳定和防护;降雨作用对边坡稳定影响极大,在坡脚积水的情况下,坡脚处塑性应变值比常态增加近20倍;地震作用促使坡脚应力和应变值升高,并且随着地震动峰值加速度的增大而变化显著。模拟分析结果为砂黄土高边坡优化设计和灾害治理提供了科学依据。
Based on field investigation and lab tests,the main failure form of the sand loess slope and its impact factors on the northern Loess Plateau are summarized in this paper.Taking for an example from the construction of high-type highways in northern Shaanxi,a series of numerical simulations have been made using the elastico-plastic finite-element method to illustrate the influences of various factors,including the slope form,rainfall and earthquakes,on the stability of sand loess slopes under the conditions of excavation by different engineering works.The simulation results indicate that: with increasing slope angle or slope height,a slope becomes gradually less and less stable;a slope with a stepped form is more stable than that with a linear form,and is favorable for protection;rainfall tremendously influences the stability of a sand loess slope,and especially in the case of water logging at the slope foot,the stain value of the slope foot increases nearly 20 times than that in a normal state;earthquakes can make the values of both the stress and strain at the slope foot increase obviously with the growth of seismic acceleration.The simulation results provide a scientific basis for the high sand loess slope design and hazard control.
Based on field investigation and lab tests,the main failure form of the sand loess slope and its impact factors on the northern Loess Plateau are summarized in this paper.Taking for an example from the construction of high-type highways in northern Shaanxi,a series of numerical simulations have been made using the elastico-plastic finite-element method to illustrate the influences of various factors,including the slope form,rainfall and earthquakes,on the stability of sand loess slopes under the conditions of excavation by different engineering works.The simulation results indicate that: with increasing slope angle or slope height,a slope becomes gradually less and less stable;a slope with a stepped form is more stable than that with a linear form,and is favorable for protection;rainfall tremendously influences the stability of a sand loess slope,and especially in the case of water logging at the slope foot,the stain value of the slope foot increases nearly 20 times than that in a normal state;earthquakes can make the values of both the stress and strain at the slope foot increase obviously with the growth of seismic acceleration.The simulation results provide a scientific basis for the high sand loess slope design and hazard control.
引文
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[2] 曲永新,张永双,陈情来.陕北晋西黄土滑塌灾害的初步研究[J].工程地质学报,2001,9(2):233～240.
[3] 张永双,曲永新,陈情来等.浅析黄土滑塌与黄土滑坡[J].工程地质学报,2002,10(S):258～262.
[4] 陈志新.黄土高边坡稳定性影响因素分析[A].全国岩土与工程学术大会论文集[C].人民交通出版社,2003,601～607.
[5] 张永双,曲永新.陕北砂黄土区公路地质灾害及其防治对策[J].中国地质灾害与防治学报,2004,15(2):35～38.
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